Frontline aspiration versus stent retriever thrombectomy for M2 occlusions: Insights from the STAR registry

BACKGROUND: Recent trials have furthered uncertainty regarding the endovascular benefit for medium vessel occlusions (MeVO). Stent retrievers (SR) were employed in the first attempt in most interventional arm participants. We sought to compare outcomes in acute MCA M2 occlusions between frontline aspiration and SR, and to delineate procedural and anatomical covariates associated with differential treatment effect. METHODS: Retrospective analysis of a multicenter stroke thrombectomy cohort identified cases of MT for M2 occlusions. Unmatched and propensity score-matched (PSM) cohorts were generated comparing frontline aspiration to standalone and combined SR. The primary outcome was functional independence (mRS 0-2) at 90 days. Recanalization, symptomatic intracranial hemorrhage (sICH), mortality, and the effect of M2 laterality, division occlusion and procedure time were assessed. RESULTS: About 1734 patients with M2 occlusions underwent either frontline aspiration (n = 711) or SR/combined (n = 958) thrombectomy between 2013 and 2024. PSM analysis favored aspiration for functional independence (49.9% vs 44.0%, OR 1.27 (1.03-1.57)), complete recanalization (61.2% vs 48.7%, OR 1.66 (1.34-2.05)), complete first pass effect (35.0% vs 27.6%, OR 1.42 (1.13-1.78)), and sICH (3.5% vs 6.2%, OR 0.55 (0.33-0.91)), with no difference in mortality. Frontline aspiration had significantly shorter procedural times (median 28 [IQR 15-49.5] vs 51 [IQR 35-78] minutes; p < 0.001). For every minute increase in procedure time, the probability of functional independence decreased significantly (p < 0.001) less with frontline aspiration (0.35%) compared to SR/combined (1.61%). CONCLUSION: Frontline aspiration for M2 occlusions resulted in better clinical and angiographic outcomes compared to SRs. Future trials for MeVO with a focus on contact aspiration thrombectomy may succeed where recent trials have failed.